Known smart valve systems and remote logic solvers can be connected to a plant-wide central monitoring computer, but such a configuration requires significant overhead in communication links among the distributed mechanisms, such as safety devices, in a process plant. Such overhead is compounded because smart valve controllers and local safety logic solvers can be separate entities each used for controlling a particular EIV.
Prior art smart valve systems include an assembly of an EIV, an actuator, a solenoid valve, a smart valve controller, a local control panel, and a plant-wide Emergency Shutdown (ESD) system. Each smart valve system uses the smart valve controller to control the travel of the EIV during routine functional testing, but relies heavily on the hard-wired input/output channels of a plant-wide ESD system for the logic required to enable local control through local control panels of individual smart valve devices and EIVs in the field.
Although some degree of local control of a safety instrumented function is provided by prior art systems, implementations of local control throughout a plant-wide ESD system have been very costly.
A need exists for integration of the logic required to perform local controls involved with a safety instrumented function for each EIV within a smart valve controller to reduce the overall ESD input/output (I/O) requirements and to provide a significant cost savings while implementing enhanced fault monitoring and detection.
Prior art implementations of a set of local control actions for each EIV to complete safety instrumented functions for each specific application have been costly.
In addition, many systems are available in the prior art which monitor devices in the field and which provide diagnostic alarms upon detection of problems of such field-based devices. However, such known systems require auxiliary computers to provide such monitoring and diagnostic functionality. In addition, operators or maintenance technicians must use a stand-alone computer with special diagnostic software to interpret the data collected during an EIV functional test and the associated test diagnostics.
Further, safety valve products in the prior art provide diagnostics remotely, but such products used in commercial processes and systems fail to provide a local indicator, mounted to devices in the field, for performing such monitoring and diagnostic functions.
A need exists for a device which simplifies operations for process plant operators and maintenance personnel by monitoring EIVs and their associated EIV control systems internally, as well as providing a local indicator of a detected fault at the time of detection, and recording valve performance data for later retrieval.
A problem with known monitoring systems of the prior art is the overload of alarms; that is, too many alarms of numerous monitoring devices in a monitoring system create human alert fatigue, which can pose a significant problem when a few serious hazardous conditions having alert indications are buried among alert indications of less serious issues.
A need exists for a straight-forward indication to personnel of problems in a plant which personnel can readily recognize as serious in order to take immediate action.
Known safety products and devices monitoring faults can track the occurrence of faults, but none provide a timeclock to track and record faults and other performance data locally, i.e., at the safety device. Accordingly, delays in transmission of clocked faults reduce the accuracy of the tracking of faults. A need exists for a locally-positioned clock to track and record detected faults and other performance data.
Known monitoring and detection systems provide limited alarm and warning capabilities. For example, U.S. Pat. No. 302,980 to Buell describes a fire extinguisher and alarm system using both local and remote central station alarm indications, but does not utilize or test EIVs using smart valve controllers.
U.S. Pat. Nos. 4,976,144 and 5,197,328 to Fitzgerald describe a diagnostic controller for testing and determining the operating condition of a pneumatically operated valve. However, the diagnostic controllers in Fitzgerald stroke a valve fully and so interrupts normal operations, and the diagnostic controller requires a portable external computer to be connected to pneumatic lines to collect data during testing.
U.S. Pat. No. 5,056,092 to Bruner describes a computer system monitor and controller using both local and remote central station alarm indications, for the purpose of entirely powering down another computer system, as opposed to testing an EIV.
U.S. Pat. No. 5,329,465 to Arcella et al. describes an on-line valve monitoring system which relies on a remotely located expert system to analyze valve data and to track and find trends in the historical data, as opposed to a local diagnostic and indicator system.
U.S. Pat. No. 5,425,316 to Malone describes a control system used in a waste disposal system which has sensors for measuring conditions throughout the waste disposal system in order to improve the efficiency of waste incineration combustion chambers, as opposed to testing EIVs.
U.S. Pat. No. 5,573,032 to Lenz et al. describes a valve positioner with pressure feedback and other diagnostic functions, but the valve positioner lacks internal diagnostics and so there cannot be any local indication of detected faults.
U.S. Pat. No. 5,586,050 to Makel et al. describes a remotely controllable management system for a liquefied natural gas (LNG) station using both local and remote central station alarm indications. However, the management system relies on a remotely located host computer for emergency warnings and shut-down features. The management system does not relate to EIVs and does not provide local fault indications based on internal diagnostics.
U.S. Pat. No. 5,684,451 to Seberger et al. describes a control system for digital communications with an instrument to perform diagnostic operations for use with an electro-pneumatic valve positioner, as opposed to performing safety related EIV on-board diagnostics and local indications of detected failures.
U.S. Pat. No. 6,089,269 to Essam describes an emergency valve connected to a partial stroke controller to perform a partial stroke test at a predetermined time, but fails to provide any on-board diagnostics and any location indication of detected failures.
U.S. Pat. No. 6,131,609 to Metso et al. describes a method and apparatus for surveying the condition of a control valve using on-board sensors, with diagnostics programmed into a digital positioner of the control valve. However, when faults are detected, such detection is communicated to a remote control system in a monitoring room in a separate control building, as opposed to a local indication of the detection of the faults.
U.S. Pat. No. 6,176,247 B1 to Winchcomb et al. describes a device for verifying the workability of a safety device, using on-board diagnostics of a safety related final element such as an EIV, and detected faults are communicated to a Remote Communications Interface (RCI), as opposed to the local indication of a fault.
U.S. Pat. No. 6,283,138 B1 to Friend et al. describes a pressure relief valve monitoring device using both local and remote central station alarm indications to detect faults in pressure relief valves, as opposed to EIVs.
U.S. Pat. No. 6,435,022 B1 to Albuaijan, based on U.S. Patent Application Publication Number US 2002/0108436 A1 to Albuaijan, describes a partial stroke testing system using a limit switch invention to control the travel of a valve during on-line testing, but lacks on-board diagnostics and local indication of detected failures.
U.S. Pat. No. 6,631,882 B2 to Mack describes a testing apparatus to test a shutdown device during operation of a process, but requires use of a remotely located programmable logic controller to perform the testing and alarm functions on detection of test failure conditions. No on-board self-diagnostics are provided, and there is no local indication of a detected fault.
U.S. Pat. No. 6,678,584 to Junk et al. describes a method and apparatus for performing diagnostics in a pneumatic control loop for a control valve, but lacks any provision of a local indication of detected dangerous faults.